AMERICAN presidents have been known to look across the Atlantic and envy the powers a British prime minister has at his disposal. The separation of powers and the limits laid down by the Constitution are designed in no small part to keep a check on the Executive.

But James Risen's new book, State of War: the History of the CIA and the Bush Administration, reveals how the Bush presidency has ignored Acts of Congress and recovered for itself much of the power Congress sought to restrain in the aftermath of the Vietnam War and Watergate.

Crucially, however, Risen also argues that because of US counter-terrorism measures "al-Qaeda now seems to lack the power to commit another 9/11".

Risen's book reveals a picture of an all but out-of-control administration, hell-bent on prosecuting the war on terror by any and all means deemed necessary, regardless of US legal impediments.

Most notably, the administration has ignored the 1978 Foreign Intelligence Surveillance Act which requires the National Security Agency to apply for a warrant if it wants to eavesdrop on telephone calls or e-mails inside the United States.

Although a warrant need only be applied for within 72 hours of a wiretap beginning - and, according to the Department of Justice, the court has denied only three surveillance requests since 1979 while allowing 18,724 - the Bush administration considers the Act an unhelpful hindrance in the war on terror.

Wiretaps without warrants are justified because, according to Vice-President Dick Cheney, "Either we're serious about fighting the war on terror, or we're not."

Cheney claimed that the only suspects being tracked are those who "always had an established link to al-Qaeda people".

Risen told NBC: "What I think that the administration really felt was the volume of phone numbers they wanted to listen to was so large, it would have been difficult to get enough search warrants in fast enough time to make this programme work. I also think that they wanted to do it in secret. They believed that it was better to keep this secret, obviously, than to make sure no one knew about it.

"They were eavesdropping on roughly 500 people in the United States every day over the past three or four years. That adds up to potentially thousands of people."

The administration argues that it is, quite literally, not subject to any law that might curtail the president's authority as commander-in-chief during a time of war.

The White House cites a Congressional resolution passed on September 14, 2001, authorising the president to use "all necessary and appropriate force" against the perpetrators of the September 11 attacks.

In this respect the administration is behaving as previous presidents have seen fit in times of national crisis. Bush has not suspended habeas corpus as Abraham Lincoln did during the Civil War, nor has he interned thousands of people as Franklin Roosevelt did during the Second World War. However, both those conflicts were of limited duration and the edicts were rescinded as soon as peace was signed.

According to Tim Naftali, an intelligence historian at the University of Virginia: "The administration is just saying, 'Trust us,' and you can't go on doing that for 20 years. At some point, you've got to regularise this, because you can't lose your soul fighting terrorism. And terrorism is a chronic problem."

President Bush argues that Iraq and Afghanistan are the two most important fronts in the war on terror. But his administration has expanded its definition of the battlefield considerably.

Asked by a federal appellate judge in July if the administration was "prepared to boldly say the United States is a battlefield in the war on terror", Paul Clement, the solicitor general replied, "I can say that, and I can say it boldly."

It is not just the White House which is targeted by the book. Risen depicts an intelligence community riven by faction and plagued by incompetence and group thinking.